I strongly suggest you to focus on one or two pairs at most. Being a translator does not mean to know multiple languages, yeah it can be helpful for personal reasons, but you will not reach that fluency that allows you to work with it. You need to specialise in one or two fields and know every little detail about the ones that you will choose. At the beginning I used to think like you, and I was learning 5-6 languages at the same time. Then, studing and knowing better the translation world I understand that it was useless. You can do it for yourself (learning more languages), but really focus your efforts in learning 2 languages and their culture and you will be a very good translator.

Good luck!